と (to), も (mo), and の (no) are three tireless particles for linking words and building relationships between nouns. They appear constantly in both dialogues and basic readings.
と connects items or people in an exhaustive list (“and”) and also means “with”: パンと卵 (パンとたまご / pan to tamago) “bread and eggs”, 友だちと行く (ともだちといく / tomodachi to iku) “I go with a friend”.
も means “also” and usually replaces は/が: 私も学生です (わたしもがくせいです / watashi mo gakusei desu) “I am a student too”.
の links two nouns and expresses possession, specification, or classification: 私の本 (わたしのほん / watashi no hon) “my book”, 日本語の先生 (にほんごのせんせい / nihongo no sensei) “Japanese teacher”. It is also the の that allows an entire clause to behave like a noun, a powerful tool you will meet often at later levels.